Replacement of Polyethylene (LDPE) and Wax Coating in Paper Cup by Alternative Coatings Dr. M. K. Marichelvam M.E., Ph.D 1* M.Nagamathan 2 1 ASSISTANT PROFESSOR 2 RESEARCH SCHOLAR DEPARTMENT OF MECHANICAL ENGINEERING MEPCO SCHLENK ENGINEERING COLLEGE SIVAKASI DEPARTMENT OF MECHANICAL ENGINEERING MEPCO SCHLENK ENGINEERING COLLEGE SIVAKASI ABSTRACT The disposable cup which is made out of paper and often lined with plastic or wax to prevent leaking and soaking of liquid from the cup. Drinking in the LDPE paper cup causes some of the health effects and also the environmental effects. The health wise effects are due to the high temperature of the hot beverages at 93 o C which is poured inside the cup which leads to the changes in film property from hard glossy material to soft rubbery material. The environmental effects are due to the burning of these used paper cups which contains LDPE film leads to the formation of toxic gases and high amount of carbon dioxide evolved which causes severe health problems. To find out these severities various tests are taken and calculated the effects by the analysis. In this work, the replacement of LDPE film in the paper cup is done by applying some of the natural gum products from the seeds of plant. Here the guar gum is selected among the various gum products based on certain criterion. The coating compositions are chosen by getting guidance from the guar gum manufacturing industries and also on the basis of trial and error method. After this the guar gum is prepared according to the composition and tests the various parameters like water absorption capacity and thermal resistance of the coating. For all the compositions made the results showed that the guar gum coating is not fit for the paper cup which is need to become a leak proof coating for the drinking beverage. KEYWORDS: Plastic, Wax, LDPE film, Guar seed, Guar gum, Hot beverages 1. INTRODUCTION A paper cup is the disposable cup which is made out of paper and often lined with plastic or wax to prevent leaking and soaking of liquid from the cup. The base paper for paper cups are called cupboard and are made of special multi-ply paper machines and have a barrier coating for waterproofing. In the earlier stage, paper cups for hot drinks were glued together and made waterproof by dropping a small amount of clay in the bottom of the cup, and then spinning at high speed so that clay would travel up the walls of the cup, making the paper water resistant. However, this resulted in drinks smelling and tasting of cardboard. Cups for cold drinks could not be treated in the same way, as condensation forms on the outside, then soaks into the board, making the cup unstable. To remedy this, cup manufacturers developed the technique of spraying both the inside and outside of the cup with wax. Clay and wax coated cups disappeared with the invention of polyethylene (PE) coated cups; this process covers the surface of the board with a very thin layer of PE, waterproofing the board and welding the seams together. Most paper cups are designed for a single use and then disposal. Very little recycled paper is used to make paper cups because of contamination concerns and regulations. Since most paper cups are coated with plastic (polyethylene), then both composting and recycling of paper cups is uncommon because of the difficulty in separating the polyethylene in the recycling process 2. PROBLEM IDENTIFICATION The following are the various problems which is due to the use of polyethylene coated paper cups, The LDPE film of density 0.910 0.940 g/cm 3, withstand a temperature range of 80 C continuously and 85 C for a short time. But the maximum temperature of serving hot drinks is about 85 C and 93 C. 19
Paper wastes are comes under the regular waste which is burnt or put in landfills. Due to the presence of plastic film, it will take more years to degrade. While burning these paper cups, dioxins are produced. It is a highly toxic pollutant, which causes cancer. 3. METHODOLOGY Review the literatures related to the paper cup. Based on the literatures, the problems are identified. Then the paper cup is initially tested with Differential scanning calorimetry to find the exact melting point of the LDPE film which is composting with the paper board. It is compared with the actual temperature of the hot drinks which being served. Then the substitute for the PE film will be developed by using guar gum and applied over the paper board and test the various parameters various parameters like Thermal resistance and Surface water absorption capacity. Then using the starch from various food products like Rice, potato, beans, and corn, a starch based coating is produced to apply on the paper board. The developed coatings are then fed under test to measure the various parameters like Thermal resistance test and Surface water absorption capacity. Finally the coating which is offering high resistance to withstand at elevated temperature and loss water absorption capacity is chosen as the best one. 4. RESULTS AND DISCUSSIONS THERMO GRAVIMETRIC ANALYSIS: From the results obtained from TGA, the mass loss for the LDPE granules is found out at various temperature ranges, which is from the room temperature to the coffee brewing temperature (93 o C) and is presented in table. Percentage of weight loss SAMPLE TEMPERATURE ( o C) WEIGHT OF THE SAMPLE % 31.09 99.78049 40 99.70539 60 99.56097 80 99.46855 93.01 99.5552 Calculation: (Weight Loss) Sample Weight = 3.728 mg Initial weight % = 99.780 Weight at 93.01 o C = 99.555 % difference in weight = 0.225% Weight loss at 93 o C = (3.728/99.780) X 0.225 = 0.0084mg TGA Analysis: LDPE chemical formula = (CH 2 -CH 2 ) n Monomer = CH 2 =CH 2 20
(CH 2 ) 2 FOOD GRADE LDPE Granule TGA Graph Atomic weight for C = 12.011 Atomic weight for H = 1.007 Total weight of (CH 2 ) 2 = 2 (12.011 + 2(1.007)) = 28.05 # 1 Test: (CH) Total weight of CH = 12.011 + 1.007 = 13.018 % of CH in (CH 2 ) 2 = (weight of CH/ Total weight of (CH 2 ) 2 ) X 100 = (13.018 / 28.05) X 100 = 46.40 % (Not Matched) # 2 Test: (C) Total weight of C = 1.007 % of CH in (CH 2 ) 2 = (weight of C/ Total weight of (CH 2 ) 2 ) X 100 = (1.007/ 28.05) X 100) = 3.59% (Not Matched) 21
# 3 Test: (H) Total weight of H = 12.011 % of H in (CH 2 ) 2 = (weight of H/ Total weight of (CH 2 ) 2 ) X 100 = (12.011/ 28.05) X 100) = 42.82% (Not Matched) The calculated % for CH, H, C are not matched with the % difference in weight (0.225%). So finally it is concluded that % difference in weight is due to the adsorbed water (Moisture) over the subjected LDPE granule material in the TGA device pan. The LDPE granule material is safe at 93 o C which is highest temperature in a coffee maker machine. PREPARING AND APPLYING THE COATING: COATING 1: The coating composition is based on the UNICARE PHARMACY COMPANY, CHENNAI. Dryer Coating composition (By weight ratio) 1:4 Mesh size = 100 mesh Paper board = 200 GSM 4 gram of water 1 gram of guar powder Heating and stirring at 80 o C for 1hr At the mid time of the process, it forms lumps and residues in the mixture that create the stirring action to fail. COATING 2: The coating composition is based on the UNICARE PHARMACY COMPANY, CHENNAI. Dryer Coating Composition (By weight Ratio) 1:4 Paper board = 200 GSM 1 gram of guar powder 4 gram of water 22
Heating and stirring at 80 o C for 1hr International Journal of Engineering Technology Science and Research Lumps formation is in fewer amounts compared to 1 st coating, but the stirring action is completely blocked after drying the coating, it came out from the applied board. So this coating composition is failed. Here after the mesh size of 100 is rejected due the residue formation COATING 3: This coating composition is based on trial and error method due to the lump formation in the coating 1 and 2. Here the volume of water is correctly find out to suit with spraying method, that means there is no lumps in the mixture that allows it to spray through the nozzle. And also small amount of glycerin is added to the mixture. The glycerin has the plasticizer property. The purpose of adding glycerin is to make the mixture yield like a plastic. The amount of glycerin is find out by adding it from 1 gram and tested in between the process of mixing by the rough paper board, whether the required amount is reached or not. Dryer Coating Composition (By weight Ratio) 1:40:5 Paper board = 200 GSM 1 gram of guar powder 40 gram of water (4 40) 5gram of glycerin (Act as a plasticizer) (1 5) Heating and stirring at 80 o C for 1hr After drying the coating surface is like a film. Then it is fed under COBB tester, after 45sec in the tester it again forms a sticky gum that leads to the adhesion of blotter paper in the tester. And also it absorbs moisture that leads to wetting of the paper board. So this coating composition is failed to meet the requirement. COATING 4: In this coating, a small amount of lemon juice is added. From the studies reported by Deepak Mudgil, the addition of acid solution will make the guar gum molecules to be easily breakdown and will react with water molecules to form a film like surface over the board. So that, a small amount of lemon juice (Citric Acid) is added to it. The correct composition is found out by testing from 1 gram to 10 grams. Finally the correct composition is found out. Dryer 23
Coating Composition (By weight Ratio) 1:40:10 Paper board = 200 GSM 1 gram of guar powder 40 gram of water 10 gram of lemon juice (1 10) Heating and stirring at 80 o C for 1hr International Journal of Engineering Technology Science and Research The coating is not uniform on the surface, after drying the lumps are formed over the surface. That forms a void over the coated surface. So this coating composition is failed. COATING 5: In this coating composition, glycerin with 1:40:10 is added and mixed to see the final coating output as a trial and error method. Dryer Coating Composition (By weight Ratio) 1:40:10:5 Paper board = 200 GSM 1 gram of guar powder 40 gram of water 10 gram of lemon juice 5gram of glycerin Heating and stirring at 80 o C for 1hr The coated surface is uniform after drying and also it appears like a film (Glare). It is fed under the COBB tester, after 45 sec in the COBB tester that coating wet the back side of the board. So this coating composition is failed to meet the requirement. COATING 6: In this coating composition, the amount of lemon juice is increased to twice to see the output coating result as a trial and error method. Dryer 24
Coating Composition (By weight Ratio) 1:40:20:5 Paper board = 200 GSM 1 gram of guar powder 40 gram of water 20 gram of lemon juice 5 gram of glycerin Heating and stirring at 80 o C 1hr International Journal of Engineering Technology Science and Research The coated surface is not uniform after drying. The film formation is slightly reduced (Glare). The coated board is softened after completely dried. So this coating composition is failed to meet the requirement. 5. CONCLUSION In this work, an attempt is made to replace the coating of LDPE film in paper cup by natural film coatings and various process measures are taken. They are the selection of guar gum from the natural gum products and it is subjected to various testing parameters like Water absorption capacity and thermal resistance test for its suitability. Finally, it is concluded that it is not suitable for the paper cup as a leak proof coating. The work may be extended to identify an alternate film for the paper in the second phase. 6. REFERENCES 1. Nashed, G., Rutgers, R.P. and Sopade, P.A (2003). The plasticisation effect of glycerol and water on the gelatinisation of wheat starch. Starch Starke, 55(3 4), pp.131-137. 2. Brown Fredericka, and Kenneth R. Diller (2008) Calculating the optimum temperature for serving hot beverages. Burns, 34(5), pp.648-654. 3. Bijayani Biswal, Sachin Kumar, and R. K. Singh, (2013) Production of Hydrocarbon Liquid by Thermal Pyrolysis of Paper Cup Waste, Journal of Waste Management. Vol.2013, pp. 1 7 4. Ibitoye, W.O., Afolabi, M.O., Otegbayo, B.O. and Akintola, A.C (2013) Preliminary studies of the chemical composition and sensory properties of sweet potato starch-wheat flour blend noodles. Nigerian Food Journal, 31(2), pp.48-51. 5. Mudgil, D., Barak, S. and Khatkar, B.S (2014) Guar gum: processing, properties and food applications A Review - Journal of food science and technology, 51(3), pp.409-418. 6. Abida Ali, Touseef Ahmed Wani, Idrees Ahmed Wani, Farooq Ahmad Masoodi, (2014) Comparative study of the physico-chemical properties of rice and corn starches grown in Indian temperate climate, Journal of the Saudi Society of Agricultural Sciences, vol.15, pp. 75 82 25